The present invention relates to a vacuum electrical switch designed to perform breaking in an electrical circuit notably a low or medium voltage circuit.
A circuit breaker of this kind is known as described in the Patent Application FR-2,682,808 filed by the applicant comprising a vacuum cartridge in which there are housed two arcing contacts, one stationary one of these contacts being securedly affixed to one of the end plates whereas the other, movable, contact is mounted with axial sliding inside the cartridge between a closed position and a position in which the contacts are separated resulting in formation of an arcing current. This circuit breaker comprises in addition a coil arranged coaxially outside the cartridge facing the separation gap of the arcing contacts, this coil being designed to produce an axial magnetic field in the arc formation zone. One of the shortcomings of this type of circuit breaker stems from the fact that the coil being connected in series with the arcing contacts, the whole of the main current flows through the coil. This results in it being necessary to provide a coil of large cross-section which therefore presents large overall dimensions and gives rise to considerable losses.
One of the solutions to this problem consists, as described in patent application Ser. No. 9,413,408 filed by the applicant, in fitting a branch-off means between the two ends of the coil, said means being designed to branch a part of the main current off through the coil during breaking in order to create a reduced axial magnetic field and thereby a reduced loss. However, in this embodiment, the thermal losses remain high.